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Reference intervals in the diagnosis of thyroid dysfunction: treating patients not numbers

Lookup NU author(s): Dr Salman Razvi



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Although the assignment of a diagnosis of thyroid dysfunction appears quite simple, this is often not the case. Issues that lead to complexities regarding whether thyroid function is, in fact, normal include transient changes in thyroid parameters, inter- and intraindividual differences in thyroid parameters, age-related differences, and ethnic variations. Superimposed upon these considerations, is the understanding that a statistically calculated distribution of thyroid analytes does not necessarily coincide with intervals or cut offs that have predictive value for beneficial or adverse health outcomes. Based on current trial data, it is unclear whether certain adults would still benefit from levothyroxine, (such as those with TSH values > 10 mIU/L), since a limited number of these persons were included in randomised trials. Even if therapy is initiated for abnormal thyroid function, not all treated individuals are maintained at the desired treatment target, and therefore still may be subject to risks. The consequence of this is that not only does each patient's thyroid function need to be assessed on an individual basis with the entire clinical picture in mind, but also monitoring needs to be vigilant, and the targets for treatment reassessed on an ongoing basis.

Publication metadata

Author(s): Jonklaas J, Razvi S

Publication type: Review

Publication status: Published

Journal: The Lancet Diabetes and Endocrinology

Year: 2019

Volume: 7

Issue: 6

Pages: 473-483

Print publication date: 01/06/2019

Online publication date: 21/02/2019

Acceptance date: 12/12/2018

ISSN (print): 2213-8587


DOI: 10.1016/S2213-8587(18)30371-1